Bulletin of the Society of Sea Water Science, Japan
Online ISSN : 2185-9213
Print ISSN : 0369-4550
ISSN-L : 0369-4550
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Volume 73, Issue 5
Displaying 1-11 of 11 articles from this issue
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Preface
Special Issue : Conservation of the Marine Environment and Promotion of Regional and Inter-Regional Cooperation for Sustainable Marine Bio-resources
Review
  • Natural Organic Substances and Microbes in Sea Water at Each Process of the Ion-exchange Membrane Salt-making System
    Izuru KAKUTA
    2019 Volume 73 Issue 5 Pages 256-264
    Published: 2019
    Released on J-STAGE: October 01, 2020
    DOIhttps://doi.org/10.11457/swsj.73.5_256
    JOURNAL FREE ACCESS
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    Changes in natural organic substances and microbes in sea water at each process of the ion-exchange membrane salt-making system were examined annually to elucidate the depositing mechanism of adherent dirt on the ion-exchange membrane. Organic substances and microbes in feeding sea water were effectively removed through two consecutive sand filtrations. However, the removal rate for polysaccharide in feeding and pretreated sea water did not meet the expected level（it decreased to 20 - 60 ％ of that in feeding sea water）. There were no considerable differences in the amount of and the composition of organic and inorganic substances and microbes deposited between the anion and the cation exchange membranes. The establishment of an effective removal system of polysaccharides loaded newly in the sand-filtration process as well as those derived from feeding sea water will be required for the suppression of ion-exchange membrane fouling in ion-exchange membrane salt-making facilities. Also, in this research it was found that（1）bacteria in adherent dirt on the membrane have a high tolerance to antibacterial and bacteriostatic agents compared to those in feeding sea water, and（2）it requires attention to biological contamination of washing solution and cleaning tools for ion-exchange membrane.
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Commentary
Lecture
Original Paper
  • Development of an Operation Support System for Electrodialysis Using IoT Technology
    Hiroshi TAKAHASHI, Yuko SHIMADA
    2019 Volume 73 Issue 5 Pages 286-291
    Published: 2019
    Released on J-STAGE: October 01, 2020
    DOIhttps://doi.org/10.11457/swsj.73.5_286
    JOURNAL FREE ACCESS
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    This paper proposes a support system for electrodialysis operation using IoT technology. In the system, solution temperature, electric current and voltage, and pH sensors are set in the electrodialysis plant, and these are serially connected to the Raspberry Pi 3 server via I/O interface modules. The acquired data is visualized graphically on the server and consequently transferred to another site server via a TCP/IP network. We developed web-accessible monitoring and a controlling program based on the Hyper Text Markup Language to operate the pumps and the power supplies of electrodialysis via the TCP/IP network. The system allows the operator to remotely monitor and control devices via a web user interface application.
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  • Performance of Multiple-Effect Diffusion Still for Seawater Concentration
    -Improved Fivefold-Effect Still Tilted at 45° with 5 mm Vapor-Diffusion Distances-
    Takehiro NOSOKO, Masaaki ISHIKAWA, Hisashi MINAKUCHI, Satoru GIMA, Tom ...
    2019 Volume 73 Issue 5 Pages 292-299
    Published: 2019
    Released on J-STAGE: October 01, 2020
    DOIhttps://doi.org/10.11457/swsj.73.5_292
    JOURNAL FREE ACCESS
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    A fivefold-effect still with 5 mm vapor-diffusion distances between evaporating and condensing surfaces was examined experimentally. Evaporating wicks were glued to metal plates, and concentrate was collected by gutters at the lower ends of the wicks. The still was tilted at a 45° degree angle, and heated on the 1×1.6 m2 bottom area and cooled on the top by means of forced convection. The experimental results were compared to theoretical ones based on a two-dimensional steady-state model. The findings are summarized as （1）Gluing wicks to metal plates with double-sided adhesive tape prevents the appearance of air bubbles under evaporating wicks, keeping hydrophilicity of the wick high enough for evaporation. （2）The experimental evaporation rates from inner wicks are smaller than the theoretical ones, suggesting that part of the condensate comes down from upper plates and mixes with concentrate. （3）Experimental total evaporation rates are smaller than the theoretical ones by 12 ％ on average. （4）Experimental heat ratios of total evaporation to condensation on the first plate are smaller than theoretical ones by 13 ％ on average.
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Commentary
Lecture
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